Technical Field
The present invention relates to a shaft structure to be installed in shafts used for various industrial machines such as vehicles, and a male component and a female component included in the shaft structure.
Description of the Related Art
Conventionally, there have been publicly well-known telescopic shafts each including male and female spline shafts to be incorporated into, e.g., vehicle steering shafts (see FIG. 2 in Patent Document 1). Such a telescopic shaft has splines formed on an outer surface of the male spline shaft and an inner surface of the female spline shaft. Furthermore, an approximately 0.25 mm thick synthetic resin (nylon or the like) coating is formed on either of the outer surface of the male spline shaft or the inner surface of the female spline shaft.
However, the telescopic shafts generate unpleasant noise, i.e., the so-called tooth-hit noise from between the male and female spline shafts, which are problematic, due to the fact that the dimensional accuracy of such a telescopic shaft is pursued with respect to the splines formed on the outer surface of the male spline shaft or the inner surface of the female spline shaft.
Meanwhile, there has been publicly well-known a torque transmission joint having rubber material such as nitrile rubber, silicone rubber, urethane rubber, and the like disposed in a gap in part between a male spline shaft and a female spline shaft (see FIG. 2 in Patent Document 2). In such a joint, rattling vibrations between the male and female spline shafts are absorbed with the rubber material, thereby resulting in the reduction of rattle noise (tooth-hit noise) generated therebetween.